Earth and water-retaining structures and bulkheads at beaches and shorelines take various forms. Incessant exposure to tides and waves in a beachfront environment usually requires cement or rock structures, including riprap, sea walls and revetment. Along the shores of bays, intercostal waterways, rivers and lakes, however, wooden bulkheads provide durable protection that is less expensive and easier to install.
One primary problem associated with wooden waterfront retaining bulkheads is that they are subject to marine borers. Such borers can, within a few years, penetrate, severely weaken and destroy bulkhead structures. The damage they impart can be insidious, because the structural integrity occasioned by massive infestation of borers may be imperceptible from the appearance of only a few holes on the surface of the structure. Such borers include mollusks such as the shipworm or teredo, a bivalve which rasps and digests wood particles for protection and nutrition, clams such as the martesia or wood piddock which can penetrate an inch or more into wood, and crustaceans such as gribbles or limnoria, sphaeroma, and chelara, whose horny jaws are particularly well adapted for boring into wood and forming interlacing burrows that can devastate structural integrity.